Spring probe pins, also known as pogo pins, have been widely used in inspection equipment for semiconductor wafers, LCD modules, camera modules, image sensors, and semiconductor packages, a variety of sockets, battery connectors of mobile phones, etc.
As shown in FIG. 1, a conventional pogo pin includes an upper probe 12, a lower probe 13, a spring 14, which is formed to apply elastic force on the upper probe 12 and the lower probe 13, and a cylindrical body 11, which contains a lower portion of the upper probe 12, an upper portion of the lower probe 13, and the spring 14.
The respective one ends of the upper probe 12 and the lower probe 13 are engaged with the cylindrical body 11 so that the upper and lower probes may not be detached from the cylindrical body 11. Furthermore, the upper probe 12 and the lower probe 13 are subject to elastic force of the spring 14 which is disposed between the upper probe 12 and the lower probe 13.
FIG. 2 is a cross-sectional view of a socket for inspection of semiconductor package in which a plurality of pogo pins are contained in an insulating body. The socket 20 for inspection of semiconductor package includes a plurality of pogo pins 6, and an insulating body 1 which contains the plurality of pogo pins at predetermined intervals. The pogo pins 6 are provided in the insulating body 1 in such a manner that upper probes 12 are projected from a top surface of the insulating body 1 and lower probes 13 are projected from a bottom surface of the insulating body 1 while the pogo pins 6 are spaced apart from one another at the same intervals as those of external terminals 3a of a semiconductor package 3, which come in contact with the upper probes 12, and at the same as those of contact pads 5a of a test board 5, which come in contact with the lower probes 13.
For inspection of the semiconductor package, when the semiconductor package 3 is pressurized, the external terminals 3a of the semiconductor package are brought into contact with the upper probes 12 of the pogo pins 6 and the lower probes 13 are brought into contact with the contact pads 5a of the test board 5. In this case, the upper probes 12 and the lower probes 13 are elastically supported by the springs 14 of the pogo pins 6 to electrically connect the semiconductor package 3 and the test board 5 to each other, thereby enabling an accurate inspection of the semiconductor package.
As shown in FIGS. 1 and 2, the pogo pins need to be positioned at the same intervals as those of the terminals of the semiconductor package. As the semiconductor package becomes increasingly smaller in size, higher in degree of integration, and more efficient in performance, the pogo pin for inspection of the semiconductor package needs to become smaller in size, i.e., in outside diameter, and have a stable, low-impedance transmission path in order to transmit high-frequency electrical signals without distortion. However, the conventional pogo pin is disadvantageous in that the conventional pogo pin is formed in such a manner that the cylindrical body is provided on the outside of the spring. In other words, the conventional pogo pin needs to have an outside diameter as large as both the outside diameter of the spring and the thickness of the cylindrical body containing the spring, which makes it difficult to reduce the outside diameter of the pogo pin to below a predetermined size. Furthermore, since the spring 14 has an electrical path in proportion to the number of turns of the spring 14 and has a spiral structure of a coil causing resistance and inductance components, the spring 14 is not suitable for the electrical path. Accordingly, the conventional pogo pin is disadvantageous in that since the conventional pogo pin has an electrical path through the upper probe 12, the cylindrical body 11, and the lower probe 13, an accurate electrical contact should be maintained at two connection points between the upper probe 12 and the cylindrical body 11 and between the cylindrical body 11 and the lower probe 13.
In addition, the conventional pogo pin is disadvantageous in that the manufacturing process is complex, the manufacturing time is long, and the manufacturing cost increases since the cylindrical body, the upper probe, the lower probe, and the spring are separately manufactured and then the upper probe and the lower probe are combined with the cylindrical body.